The subject invention relates to an apparatus for mounting impellers on rotatable tables in centrifugal impact crushers, and in particular to such an apparatus which does not use mechanical fasteners to secure the impellers to the table.
Centrifugal impact crushers deposit the material being crushed on to a rotating horizontal table. Centrifugal force throws the material radially off of the table against anvils which causes the material to be fractured. In order to direct the material so that it leaves the table with the proper projection to maximize fracture when it hits the anvils, impellers are placed at spaced intervals on the table. Due to the severe forces and shock loading that these impellers are subject to they typically are bolted or pinned to mounting brackets that are attached to the table. However, the bolt heads or pins become damaged by being impacted by the material being crushed and the material cakes around the bolt heads or pins, both of which makes it difficult to remove the bolts or pins when it is necessary to replace a worn impeller. As a result, it is desirable to secure the impellers to the table without the need for bolts or similar mechanical fasteners. This must be accomplished in a way that rigidly holds the impellers in place, however, in spite of the severe forces that tend to knock them loose.
While systems for securing impellers to the table without mechanical fasteners are known, these systems do not provide both the necessary rigidity and ease of removal of the impeller for replacement Parker, U.S. Pat. No. 3,540,667, discloses an impeller that has a hook along its inner edge that fits behind an inwardly protruding ledge in-the mounting bracket. While this system certainly provides for easy replacement of the impellers, the impellers can become displaced in use. Wood, U.S. Pat. No. 3,474,974, also discloses an impeller which is attached to the mounting bracket by means of a hook. Unlike Parker, however, Wood mechanically secures the hook to the mounting bracket.
It is common in centrifugal impact crushers to mount the anvils to their mounting brackets merely by inserting a projecting tab with an enlarged head at its end into a slot in a mounting bracket. Such an arrangement is shown in Rose, et al., U.S. Pat. No. 5,137,220, Krause, et al., U.S. Pat. No. 4,659,026 and Wood, U.S. Pat. No. 3,474,974. However, unlike impellers, anvils are not subject to centrifugal force which tends to lift them out of the slots, and the weight of the anvils will hold them in place against any lifting force caused by the impact of the material being crushed.
The subject invention overcomes the limitations and short comings of the prior art impeller mounting systems. A preferred embodiment of the invention provides a series of mounting plates which are attached to the crusher table. Each mounting plate has a slot which extends between its front and rear surfaces and opens out of its top surface. An impeller has a stob projecting from its rear or mounting face which slidably fits within the slot. A nub mounted on the extremity of the stob is configured so that it will not fit through the slot. The stob and nub are arranged to interact with the mounting bracket to prevent movement of the impeller with respect to the mounting bracket in either circumferential direction. The slot has opposed sides which are angled radially outwardly as they extend toward the table. Thus, centrifugal force will not lift the stob out of the slot as the table is rotated. -The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.